期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2014
卷号：111
期号：17
页码：E1705-E1712
DOI：10.1073/pnas.1400577111
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The histidine imidazole side chain plays a critical role in protein function and stability. Its importance for catalysis is underscored by the fact that histidines are localized to active sites in [~]50% of all enzymes. NMR spectroscopy has become an important tool for studies of histidine side chains through the measurement of site-specific pKas and tautomer populations. To date, such studies have been confined to observable protein ground states; however, a complete understanding of the role of histidine electrostatics in protein function and stability requires that similar investigations be extended to rare, transiently formed conformers that populate the energy landscape, yet are often "invisible" in standard NMR spectra. Here we present NMR experiments and a simple strategy for studies of such conformationally excited states based on measurement of histidine 13C{gamma
关键词：conformationally excited protein states ; Im7 protein-folding intermediate ; chemical exchange ; pH stability ; CEST
